1. Field of the Invention
The present invention relates to generic electronic safe and arm (ESA) devices based on a universal building-block application specific integrated circuit (ASIC) . This universal ASIC ESA is suitable for applications including missiles, rockets, artillery, mortar, mines, and submunitions.
2. Description of the Prior Art
Fuzes require some methods to prevent accidental initiation of the explosives during storage, shipping, handling, and for safe operation after launch by the delivery system. Traditionally this has been done with a mechanical or electromechanical safe and arm (S&A) which kept the sensitive explosives in the warhead out of line with the secondary explosives. After launch, the S&A would sense some unique environmental changes such as high acceleration, spin, or airflow which would release mechanical locks, allowing the sensitive explosives to move in line to set up the firing train.
An all electronic S&A has the potential to improve the safety and reliability of fuzes. This type of S&A replaces the sensitive explosives with secondary explosives in an in-line explosive train. This explosive train is initiated by an exploding foil initiator (EFI). The EFI is a small piece of metal foil on plastic (typically copper on Kapton[trademark]). The EFI is functioned by discharging electrical energy at a high voltage into the device at a very rapid rate. This discharge causes the metal foil to vaporize and form and accelerate a plastic flyer to a high velocity. This flyer impacts the lead charge of the explosive train and causes direct shock initiation.
The exploding foil initiator (EFI) , also known as the slapper detonator was developed by the DOE National Laboratories (Sandia, Los Alamos, Lawrence Livermore) in the mid 1970's for unconventional weapon applications. DOD organizations have also investigated EFI initiated, in-line explosive train technology for conventional munition applications, with an electromechanical S&A. These applications include Air Force bombs and Navy missiles.
One of the first applications for an ESA was the FOG-M Missile. The development of the ESA for this missile began in 2nd Qtr, FY86 as a U.S. Army MICOM sponsored project at Sandia National Labs with collaboration by Harry Diamond Labs. This joint effort resulted in the development of a working ESA. In addition, safety logic architectural concepts were formulated which were adopted by the Army Fuze Safety Review Board (AFSRB) as a recommended configuration. Some features of these concepts have become almost universal in US ESA applications. The most salient features of these concepts were the use of three electronic arm path interrupters (two static and one dynamic), multiple environmental signature processing, safety logic comprised of a microprocessor or microcontroller combined with additional logic devices and the concept of dynamic arming.
All known ESA developments to date employ safety logic which fits into one of the following categories.
a microcontroller (uc) combined with standard discrete logic devices (from a manufacturers catalog and typically multisourced), PA1 a microcontroller (uc) combined with standard programmable logic devices (glue logic), PA1 a uc combined with multiple application specific integrated circuits (ASIC)-two different ASIC'S, both digital or one digital and one analog, PA1 all ASIC logic-typically two complex, digital complementary metal oxide semiconductors (CMOS) ASIC'S, PA1 all standard discrete digital "state machine" logic with counter addressed large read only memories (ROM)s and additional logic, or PA1 all standard discrete digital logic. PA1 multiple power and ground pins on the ASIC, PA1 redundant power up reset functions (within the ESA), PA1 an architecture which clearly identifies safety critical elements, PA1 a command arm/data link register that can be interrogated by the microcontroller during a mission and which will receive data at a high rate or will provide a unique code word to complete a software oscillator or to compare to a data bus "good guidance" or "command arm" word, PA1 safety critical status of the microcircuit that can be chosen for a particular application, PA1 bi-phase ASIC input functions wherein one input is inactive in the low state and the other input is inactive in the high state and both inputs must change to the opposite state to become active, and PA1 "shielding" for the pins of safety critical functions; e.g., an arm switch output which is inactive in the low state and is positioned between two ground pins.
In these applications, non-standard devices such as ASIC's are developed and configured like ordinary commercial devices They are without specific safety enhancing features. The problems and disadvantages to implementing ESA safety logic with these approaches are numerous and include:
The configuration of many of these designs masks or makes it difficult to identify elements critical to the arming process (safety critical);
Many of these designs are needlessly complex with greater than necessary development cost, risk, and component cost;
None of these designs makes good use of safety enhancing techniques such as multiple power and ground pins and specific architectural features; and the designs which do not include a microcontroller (uc) have limited computing power for processing sensor and data bus signals or performing arithmetic operations.
Accordingly, it is an object of this invention to provide a universal building block Application Specific Integrated Circuit (ASIC) which is used multiple times in an Electronic Safe and Arm (ESA) rather than using several ASIC designs in an ESA system thereby enabling one to configure an ESA for many applications.
It is another object of this invention to provide unique safety enhancing features in the ESA consisting of: